I’M JUST OUTSIDE BOZEMAN, leaning against a rail fence beside a dandelion-strewn meadow, gazing up at a ridge dotted with fir trees. Nearby, winding through a birch grove, is a stream about 10 feet wide, the bottom churned up by the spring snowmelt on this May morning. From a stony beach that widens into the channel, I can see the Bridger Mountains across the valley, heavily treed and glowing in the sun. This is the Montana of my dreams.

Over the next week, I aim to play rugby in Missoula, swim across a glacial lake near Whitefish, bicycle up some 6,000 feet on the Going-to-the-Sun Road, and raft down the Stillwater River. Lord willing and the creek don’t rise.

Maggotfest tournament. (Rugby teams are famous for their hospitality, and experienced players can easily pick up a game at the annual Maggotfest, held in early May.) The pitch is dry and hard, and there’s a frightening moment when our scrum disintegrates like a Russian used car, but we manage to win both games. Afterward, it feels like I got hit by a freight train, then run over by a truck. Our fullback, Ryan Swan, a former Bulls teammate of Pierce’s, tosses me a cold beer. “Pour some fun down your throat,” he says.

My college roommate, “Surfer” John Hearin, arrives in time for a beer after driving all the way from Florida in his pickup. (Surfer and I are heading up to Glacier National Park before rendezvousing with Pierce, Swan, and two others down on the Stillwater River.) Over the years, my old roommate and I have gone white-water rafting in Switzerland, run with the bulls in Pamplona, taken rugby tours to Argentina and Wales, the works. Soon the two of us are headed toward Whitefish in the northwest corner of the state, cruising through the rangelands with jagged snow-covered peaks in the distance. Neil Young is singing “After the Gold Rush” on the radio as we climb a hill, and there’s the Continental Divide: the sharpened wall of the Mission Mountains on the road to Kalispell.

Established in 1910, Glacier National Park (406-888-7800, nps.gov/glac) was linked to Canada’s Waterton Lakes National Park in 1932, creating the world’s first international peace park. Some parts of Glacier are accessible year-round, but most of the 13 campgrounds open in mid- to late May, depending on the weather (and sequestration). Sites are $20 a night, first come, first served, at the Sprague Creek Campground (888-275-8747, nps.gov/findapark), located about 9 miles from the west entrance of the park on the shore of Lake McDonald. We plan to spend three nights at the campground. From this location, hardy adventurers can try some of the best hiking, paddling, glacier skiing, road and mountain biking, and open water swimming in the continental United States.

On our way to set up camp, we spot a black bear along the shore. Before dinner we take a trial swim to gauge the temperature of the water. (We had our own wet suits, but you can rent online at wetsuitrental.com.) The alpenglow lingers over Mount Vaught until nearly 10 p.m. Then Surfer hangs a can of bear spray inside the tent, and it’s off to sleep in our down bags. Around 3 a.m., something wakes me, and I stagger outside. Temperatures have dropped into the 20s, and myriad stars shine in whorls like something from a van Gogh painting, with the lake reduced to a black void beyond the embankment. I’ve awakened to my ideal landscape, the sort of place I imagine while stuck in Boston traffic or at the dentist.

At daybreak, Surfer says, “Wake up and have fun.” We’re headed for the 145-acre Lake Five, located just outside Glacier. On shore, we don our wet suits and booties as the sun rises over the lake. When I dive in, the 50-degree water tightens my throat, constricts my chest muscles, and pushes all the air from my lungs.

Loosing a primal scream, I gasp, “No way that chick floated on that door in Titanic. She was dead in two minutes.”

Surfer laughs and starts pulling for the opposite shore. The water, 60 feet deep, is so cold it numbs my skull, but when I reach a shuttered boathouse a half mile away, I stand in waist-deep water, chest heaving, a gorgeous blue sky vaulted overhead. A minute later, I head back, the sun glinting in diamond patterns on the surface of the lake.

The next day, Surfer and I carbo-load on a breakfast of oatmeal and peanut butter-banana-Vegemite enchiladas (we wisely store our grub in a communal “bear box”). Bisecting Glacier, the 50-mile Going-to-the-Sun Road meanders up and over the divide between Lake McDonald and St. Mary Lake. We plan to cycle 11 miles uphill to where the route has been blocked by an avalanche, then whiz down in a spree. Surfer has his bicycle in the truck, but I’ve rented one for $30 a day from the laid-back dudes at Glacier Cyclery (406-862-6446, glaciercyclery.com) in Whitefish.

Mid-May is the sweet spot for Glacier, as road repair and avalanches prohibit motorized traffic, yet most days it’s warm enough for a single layer of high-tech clothing. The road is flat over the early miles, winding alongside the rushing green torrents of McDonald Creek. The forest occasionally gives way to dramatic views of nearby peaks, with cascades of snowmelt pounding over the ridgeline in temporary waterfalls.

Ahead, the snowy bulwark of Heavens Peak rises to 8,987 feet, and as we ascend toward the Loop, where the road jackknifes sharply, doubling back to climb higher on the ridge, I shift into ever-lower gears, the perspiration stinging my eyes. Our ascent culminates in a 6 percent grade, forcing my heart rate close to maximum. But the payoff is the view: enormous peaks studded with ancient trees, like sentinels all around, hemming us in. Down in the valley, McDonald Creek is a green ribbon threaded between dark patches of forest.

At Weeping Wall, 90 minutes into the climb, we’ve gained a couple thousand feet in elevation, and I’m totally gassed. Lunch consists of energy bars and water; our legs dangle over the retaining wall, 2,000 feet of ether separating us from the valley below. Zooming back downhill is like returning to childhood on a two-wheeled time machine.

***

THE NEXT MORNING we drive 380 miles south, making a stop in Helena, and stay overnight near Billings. The highlight of the following day: rafting down the Stillwater River, a tributary of the Yellowstone, with Chris Pierce and his wife, Tanya, Ryan Swan, and Brock Ping. Ping is a former Billings Bulls teammate of Pierce and Swan and an expert paddler. Coming from Highway 78, he pulls off North Stillwater Road with a raft, paddles, and life jackets. (Several companies in the area, including Absaroka River Adventures, 800-328-7440, absarokariver.com, offer guided river trips.) The river is about 50 feet across at this point, running high on snowmelt and churning up sediment. Ping expects some Class 3 or 4 rapids, but mostly we’ll run on the current, paddling to avoid exposed rocks and other potential snags.

Clear skies, but an ominous cloud bank is hovering to the west. Three whitetail deer freeze like lawn ornaments when we round the first bend, then turn up their rumps and bound away. Later, Tanya Pierce spots an American bald eagle soaring above us, its white crown shining in the sun. It’s thrilling to watch an apex predator at work.

At noon, we paddle ashore and eat sandwiches made with local bread, almond butter, dark greens, and tomatoes. When we get underway again, a great blue heron starts up from the embankment, flapping right past the raft. The heron is a smoky blue-gray color, camouflaged for the terrain, a prehistoric-looking creature that seems to move slowly through the air.

An hour later, we reach the tumultuous confluence of the Stillwater and Yellowstone rivers. Rain pelts the raft, and the air has grown raw. Directly ahead is a highway bridge with four huge concrete pilings. The river swirls around the abutments, and Ping says, “I hate man-made obstacles. They’re the most dangerous parts of the river.”

As we approach, the current sucks us toward the bridge, swinging our stern toward the hole formed by the nearest abutment. Ping shouts, “Backwater right,” and digging at the river, we just barely lip out of the whirlpool. As the shadow of the bridge passes overhead, I glance at Surfer. He makes a beer-drinking motion and laughs.

***

Montana

GETTING THERE

From Boston, fly to Bozeman; you’ll need to change planes once. Rent a car in Bozeman, and drive 300 miles north to Glacier National Park, approximately a five-hour trip.

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